SNOA930C March   2015  – May 2021 LDC0851 , LDC1001 , LDC1001-Q1 , LDC1041 , LDC1051 , LDC1101 , LDC1312 , LDC1312-Q1 , LDC1314 , LDC1314-Q1 , LDC1612 , LDC1612-Q1 , LDC1614 , LDC1614-Q1 , LDC2112 , LDC2114 , LDC3114 , LDC3114-Q1

 

  1.   Trademarks
  2. 1The Sensor
    1. 1.1 Sensor Frequency
    2. 1.2 RS and RP
      1. 1.2.1 AC Resistance
      2. 1.2.2 Skin Effect
  3. 2Inductor Characteristics
    1. 2.1 Inductor Shape
      1. 2.1.1 Example Uses of Different Inductor Shapes
    2. 2.2 Number of Turns
    3. 2.3 Multiple Layers
      1. 2.3.1 Mutual Inductance of Coils in Series
      2. 2.3.2 Multi-Layer Parallel Inductor
      3. 2.3.3 Temperature Compensation
    4. 2.4 Inductor Size
    5. 2.5 Self-Resonance Frequency
      1. 2.5.1 Measurement of SRF
      2. 2.5.2 Techniques to Improve SRF for Wire-wound Inductors
  4. 3Capacitor Characteristics
    1. 3.1 Capacitor RS, Q, and SRF
    2. 3.2 Effect of Parasitic Capacitance
      1. 3.2.1 Recommended Capacitor Values
    3. 3.3 Capacitor Placement
  5. 4Physical Coil Design
    1. 4.1 Example Design Procedure Using WEBENCH
      1. 4.1.1 General Design Sequence
    2. 4.2 PCB Layout Recommendations
      1. 4.2.1 Minimize Conductors Near Sensor
      2. 4.2.2 Sensor Vias and Other Techniques for PCBs
  6. 5Summary
  7. 6References
  8. 7Revision History

3.2.1 Recommended Capacitor Values

For most application, a sensor capacitance of 300 pF to 2 nF is generally recommended unless a specific sensor frequency is needed. For some touch-on-metal applications in which the sensor is placed very close to the conductive target, smaller sensor capacitances down to 47 pF may be optimum.